ABSTRACT
Recent years have seen a large increase in the number of investigators studying brain pathology and neural repair. Many basic neuroscience studies are now devoted to the study of disease models as well as the means to repair injury, disease, or degeneration. Additionally, numerous studies are designed to “create” a pathologic
state by disrupting genes of interest. These types of studies require the neuroscientist to be able to discern changes in brain function or structure as a result of both the pathologic state as well as alterations due to therapeutic interventions. Such information can often only be obtained by sacriÞce of the animal and histologic or biochemical observation of the brain. Obviously, this approach has its limitations. First, the use of histologic outcomes precludes the longitudinal studies of individual animals. Changes that may occur as a result of an intervention have to be inferred by examining populations prior to and at different times following intervention. The groups then must be statistically compared to each other. While often useful, these types of studies require the use of extremely large numbers of animals. Furthermore, this type of investigation would tend to underestimate the signiÞcance of variation between animals, potentially missing distinctions between groups of responders and nonresponders. Ideally, one would like to have the ability to make repeated observations in individual animals. The ability to make repeated observations would not only allow for the investigator to more accurately assess interanimal variability, it would also allow for a direct analysis of change over time due to a given intervention as well as enhance the ability to make both short term and long term observations.
